Cylinder 7 Misfire Detected
What it means
This code appears mostly on eight-cylinder engines and means the engine computer has seen cylinder 7 repeatedly fail to fire. The shaking may be milder than on smaller engines because the other cylinders cover part of it, but the risk to the catalytic converter is the same.
Symptoms4
- Mild shaking or stumbling at idle.
- Slight loss of performance the driver may not notice at first.
- Check engine light on, possibly flashing under load.
- Fuel smell from the exhaust or higher consumption.
Possible causes6
- Worn or fouled spark plug in cylinder 7.
- Weak ignition coil for cylinder 7, or a damaged plug wire on engines that use wires.
- Clogged or faulty cylinder 7 injector.
- Wiring or connector damage from heat of the nearby exhaust manifold.
- Vacuum leak on that side of the intake manifold.
- Low compression or a valve problem (less common).
How to diagnose5
- Locate cylinder 7 using the manufacturer's numbering, since it differs between engines.
- Watch the cylinder 7 misfire counter and confirm the misfire is limited to it.
- Inspect the plug and its wire or coil for burn marks or cracks.
- Swap the coil or wire with another cylinder and see whether the misfire moves.
- Check the injector, then have a compression test done if the fault remains.
How to fix6
- Replace the spark plug, preferably the full set if it is due.
- Replace the faulty ignition coil or plug wire.
- Repair damaged wiring and route it away from heat.
- Clean or replace the injector.
- Repair low compression if confirmed.
- Clear the codes, drive and confirm the code does not return.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
The cost is low with a plug or coil, a bit higher than on small engines because parts and access cost more on larger engines, and higher again if an injector is needed.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026
Frequently asked questions
The engine barely shakes. Can I ignore the code?
No. On large engines the shaking can be mild, but unburned fuel still reaches the catalytic converter, overheats it and damages it over time.
Could a spark plug wire be the cause?
Yes, on engines that use wires, especially if the wire runs near the hot exhaust manifold. Check it for cracks or burn marks.
This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.
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